Valve mechanism for controlling release of pressurized fluid

ABSTRACT

A valve mechanism for controlling release of pressurized fluid includes a fluid chamber. A plunger is received in an aperture in the fluid chamber, and is movable between a fluid retention position in which fluid is substantially trapped in the fluid chamber and a fluid release position in which fluid can escape from the fluid chamber through passages in the plunger. The plunger is biased into the fluid retention position. A driver drives a plunger actuator, and the plunger actuator is guided into engagement with the plunger to cause the plunger and the plunger actuator to move in unison and move the plunger into the fluid release position during a first portion of a stroke of the driver towards the fluid chamber, and the plunger actuator is further guided to permit the plunger to return to the fluid retention position during a second portion of the stroke.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/710,288 filed on Feb. 22, 2010, which claims priority from U.S.Provisional Application No. 61/154,713 filed on Feb. 23, 2009 and U.S.Provisional Application No. 61/294,099 filed on Jan. 11, 2010, theteachings of each of which are hereby incorporated by reference in theirentirety.

FIELD OF INVENTION

The present invention relates to valve mechanisms, and more particularlyto valve mechanisms for metering discharge of a fluid.

BACKGROUND OF THE INVENTION

Clogged drains can present an annoying and potentially serious problem.Many different types of material can form or be incorporated into adrain clog, and different types of chemical drain cleaners are known.Some of these chemical drain cleaners are potentially hazardous.

The use of pressurized gas to clear clogged drains is also known.Typically, a user will place the outlet of a gas-based drain clearingdevice against the mouth of the drain to be cleared, and apply pressureto an actuator, which causes a valve to be opened so that thepressurized gas flows into the drain to remove the clog. Typically, thevalve will stay open as long as pressure continues to be applied to theactuator, which can result in too much gas being released into thedrain, potentially damaging it. One solution to this problem is toprovide a single-use cartridge containing a measured amount of gas, butthis approach requires the cartridge (or the device, where the cartridgeis integral thereto) to be replaced each time the drain clearing deviceis used. This can be particularly inconvenient for stubborn drain clogswhich require more than one burst of gas to be removed.

In addition to drain clearing devices, there are other applications inwhich metered release of a pressurized fluid is desirable.

SUMMARY OF THE INVENTION

In one aspect, the present invention is directed to a valve mechanismfor controlling release of pressurized fluid. The valve mechanismcomprises a housing and a fluid chamber defined within the housing, withthe fluid chamber defining an interior volume and having a fluid chamberinlet and a plunger aperture. The valve mechanism further comprises aplunger having a closed end and a plunger outlet end. The plunger has atleast one plunger fluid passage extending partially along a length ofthe plunger from the plunger outlet end, and has at least one plungerinlet defined in a longitudinal wall thereof in fluid communication withthe at least one plunger fluid passage. The plunger is slidably receivedin the plunger aperture in sealing engagement therewith, with the closedend within the interior volume of the fluid chamber, so as to be movablebetween a fluid retention position in which the at least one plungerinlet is isolated from the interior volume of the fluid chamber and afluid release position in which the at least one plunger inlet is influid communication with the interior volume of the fluid chamber. Thevalve mechanism further includes a plunger biasing member acting betweenthe plunger and the housing to bias the plunger into the fluid retentionposition. The valve mechanism additionally comprises a driver having adriving end and a driver outlet end and having at least one driver fluidpassage extending therethrough between the driving end and the driveroutlet end. The driver is slidably received within the housing. Thevalve mechanism also comprises a plunger actuator having a plungeractuator inlet end and a plunger actuator outlet end, and at least oneplunger actuator fluid passage extending therethrough between theplunger actuator inlet end and the plunger actuator outlet end. Theplunger actuator is received within the housing between the plunger andthe driver. The valve mechanism includes a guide mechanism for guidingthe plunger actuator into engagement with the plunger to cause theplunger and the plunger actuator to move in unison and move the plungerinto the fluid release position during a first portion of a stroke ofthe driver towards the fluid chamber when the valve mechanism isoriented with the plunger actuator above the driver, and further guidingthe plunger actuator to permit the plunger to return to the fluidretention position under urging from the plunger biasing member during asecond portion of the stroke of the driver towards the fluid chamberwhen the valve mechanism is oriented with the plunger actuator above thedriver. At least when the plunger is in the fluid release position, theat least one plunger fluid passage is in fluid communication with the atleast one plunger actuator fluid passage and the at least one plungeractuator fluid passage is in fluid communication with the at least onedriver fluid passage.

In an embodiment, following completion of the stroke of the drivertowards the fluid chamber and release of external force acting on thedriver, the plunger actuator and the driver return to their respectivepre-stroke positions when the valve mechanism is oriented with theplunger actuator above the driver. In a particular embodiment, theplunger actuator and the driver return to their respective pre-strokepositions under gravity when the valve mechanism is oriented with theplunger actuator above the driver.

In an embodiment, the at least one plunger fluid passage comprises asingle plunger fluid passage and the plunger actuator inlet end is sizedto fit within the single plunger fluid passage, and the plunger has aperipheral rim surrounding the single plunger fluid passage at theplunger outlet end. The plunger actuator inlet end of the plungeractuator engages the peripheral rim at the plunger outlet end during thefirst portion of the stroke of the driver towards the fluid chamber whenthe valve mechanism is oriented with the plunger actuator above thedriver, and the plunger actuator inlet end moves into registration withthe single plunger fluid passage so that the plunger actuator inlet endis received within the single plunger fluid passage to permit slidingmovement of the plunger toward the plunger actuator during the secondportion of the stroke of the driver towards the fluid chamber when thevalve mechanism is oriented with the plunger actuator above the driver.In a particular embodiment, the guide mechanism comprises the drivingend of the driver having a driver engagement face and the plungeractuator outlet end having a plunger actuator engagement face, with atleast one of the driver engagement face and the plunger actuatorengagement face being shaped to direct the plunger actuator inlet end ofthe plunger actuator to engage the peripheral rim at the plunger outletend during the first portion of the stroke of the driver towards thefluid chamber when the valve mechanism is oriented with the plungeractuator above the driver.

In a more particular embodiment, the guide mechanism further comprises aguide channel defined in the housing, the guide channel being sopositioned within the housing and having a surface shaped to guide theplunger actuator inlet end into registration with the single plungerfluid passage during the second portion of the stroke of the drivertowards the fluid chamber when the valve mechanism is oriented with theplunger actuator above the driver. In such an embodiment, the plungeractuator inlet end may be narrower than the plunger actuator outlet endand the guide channel may have a narrow end adjacent the plunger and awide end adjacent the driver and taper between the wide end and thenarrow end.

In one aspect, the present invention is directed to a drain clearingdevice comprising a valve mechanism as described above and a fluidreservoir having a sufficient quantity of sufficiently pressurized gasdisposed therein, with the fluid reservoir being in fluid communicationwith the fluid chamber inlet. In one embodiment of such a drain clearingdevice, the fluid reservoir consists of a separate cartridge securedwithin a cartridge cavity in a main body of the drain clearing device. Adrain clearing device according to an aspect of the present inventionmay include an external actuator movably secured to the housing andmechanically coupled to the driver to cause sliding movement of thedriver toward the fluid chamber when the external actuator moves towardsthe fluid chamber. In a particular embodiment, the external actuator maybe an outlet fitting for sealingly engaging a drain, and the outletfitting may be secured to an outlet end of the drain clearing device andhave an outlet aperture in fluid communication with the driver fluidpassage.

A drain clearing device as described above may further comprise acartridge insertion aperture at one end of the main body, a cartridgepiercer disposed at an opposite end of the cartridge cavity from thecartridge insertion aperture, and a cartridge cavity closure cap. Thecartridge cavity closure cap is removably securable to the main body toobstruct the cartridge insertion aperture and push an outlet end of thefluid cartridge into engagement with the cartridge piercer and close thecartridge cavity. The cartridge cavity closure cap is constrained,during removal thereof from the main body, to move through anintermediate position in which the fluid cartridge is released fromengagement with the cartridge piercer while the cartridge cavity closurecap remains secured to the main body and the cartridge cavity is ventedto ambient. In a particular embodiment, the cartridge insertion apertureis defined by a hollow threaded shaft portion having at least one ventdefined therein in fluid communication with the cartridge cavity, andthe cartridge cavity closure cap is correspondingly threaded forthreaded engagement with the threaded shaft portion. Removal of thecartridge cavity closure cap consists of unscrewing the cartridge cavityclosure cap from the threaded shaft portion of the main body, and in theintermediate position the cartridge cavity closure cap has beenunscrewed past the at least one vent to expose the at least one ventwhile the cartridge cavity closure cap remains threadedly secured to themain body.

In another aspect, the present invention is directed to a device forcontrolled release of pressurized fluid. The device comprises a mainbody defining a cartridge cavity and a cartridge insertion aperture atone end of the main body, a cartridge piercer disposed at an oppositeend of the cartridge cavity from the cartridge insertion aperture, andan outlet. The device further comprises a valve mechanism in fluidcommunication with the outlet for selectively permitting gas from thecartridge to be expelled from the outlet. The valve mechanism includesan inlet connectable in fluid communication with a cartridge received inthe cartridge cavity, and a cartridge cavity closure cap removablysecurable to the main body to obstruct the cartridge insertion apertureand push an outlet end of the fluid cartridge into engagement with thecartridge piercer and close the cartridge cavity. The cartridge cavityclosure cap is constrained, during removal thereof from the main body,to move through an intermediate position in which the fluid cartridge isreleased from engagement with the cartridge piercer while the cartridgecavity closure cap remains secured to the main body and the cartridgecavity is vented to ambient. In a particular embodiment, the cartridgeinsertion aperture is defined by a hollow threaded shaft portion havingat least one vent defined therein in fluid communication with thecartridge cavity, and the cartridge cavity closure cap iscorrespondingly threaded for threaded engagement with the threaded shaftportion. Removal of the cartridge cavity closure cap consists ofunscrewing the cartridge cavity closure cap from the threaded shaftportion of the main body, and the intermediate position is a point atwhich the cartridge cavity closure cap has been unscrewed past the atleast one vent to expose the at least one vent while the cartridgecavity closure cap remains threadedly secured to the main body. Thedevice for controlled release of pressurized fluid may be a drainclearing device.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the invention will become more apparent fromthe following description in which reference is made to the appendeddrawings wherein:

FIG. 1 is a perspective view of an exemplary drain clearing deviceaccording to an aspect of the present invention;

FIG. 2 is an exploded view of the drain clearing device of FIG. 1;

FIG. 3 is a cross-sectional view of the drain clearing device of FIG. 1,showing overall assembly thereof;

FIG. 3A is a cross-sectional view of a portion of the drain clearingdevice of FIG. 1, prior to commencement of a stroke of a driver thereoftoward a fluid chamber thereof;

FIG. 3B is a cross-sectional view of a portion of the drain clearingdevice of FIG. 1, during an initial stage of a first portion of thestroke of the driver thereof toward the fluid chamber thereof;

FIG. 3C is a cross-sectional view of a portion of the drain clearingdevice of FIG. 1, during a subsequent stage of a first portion of thestroke of the driver thereof toward the fluid chamber thereof;

FIG. 3D is a cross-sectional view of a portion of the drain clearingdevice of FIG. 1, during completion of a second portion of the stroke ofthe driver thereof toward the fluid chamber thereof;

FIG. 4A is a cross-sectional view of an upper portion of the drainclearing device of FIG. 1, with a cartridge cavity closure cap securedto a main body of the drain clearing device;

FIG. 4B is a cross-sectional view of an upper portion of the drainclearing device of FIG. 1, with the cartridge cavity closure cappartially removed and still threadedly secured to the main body of thedrain clearing device;

FIG. 5A shows a first exemplary embodiment of a fluid cartridge;

FIG. 5B shows a second exemplary embodiment of a fluid cartridge; and

FIG. 5C shows a third exemplary embodiment of a fluid cartridge.

DETAILED DESCRIPTION

Referring now to FIG. 1, a drain clearing device according to an aspectof the present invention is shown generally at 10. The drain clearingdevice 10 has a reservoir end 18 and an outlet end 20, and the exteriorof the drain clearing device 10 is defined by a main body 12, acartridge cavity closure cap 14, an outlet end cap (not shown in FIG. 1)and an outlet fitting 16.

Turning now to FIG. 2, the external and internal components of the drainclearing device 10 are shown in exploded view. Received within the mainbody 12 are a cartridge receiving member 22, a cartridge seal 24, acartridge piercer 26, a fluid chamber member 28, a plunger biasingmember 30 (a coil spring in the exemplary embodiment shown), a plunger32, a fluid chamber seal 34, a guide collar 36, a plunger actuator 38, adriver 40, a driver receiver member 42 and a grommet 44, and the outletend cap 46 retains the foregoing components within the main body 12. Themain body 12, the cartridge receiving member 22, the fluid chambermember 28, the guide collar 36, driver receiver member 42 and outlet endcap 46 each form part of an overall housing. As can be seen, thecartridge cavity closure cap 14 and the outlet end cap 46 are threadedlyreceived by the main body 12, and the outlet fitting 16 includes an endpiece 48.

With reference now to FIG. 3, assembly of the various components isshown. When in use, a fluid cartridge 50 is removably received within acartridge cavity 52 defined in the main body 12 of the drain clearingdevice 10. The fluid cartridge 50 is thus a reservoir of fluid, which(as will be described in greater detail below) can be selectivelyexpelled from the outlet 150 at the outlet end 20 of the drain clearingdevice 10 to assist in clearing a blockage in a drain. The fluidcartridge 50 is preferably a carbon dioxide (CO₂) cartridge ofconventional design, comprising a generally cylindrical metal canister54 of sufficient strength and having a quantity of pressurized CO₂contained therein, and having a thin metal seal 56 at an outlet endthereof. To install the fluid cartridge, a user would unscrew thecartridge cavity closure cap 14, slide the fluid cartridge 50 throughthe cartridge insertion aperture 160 into the cartridge cavity 52 in themain body 12 of the drain clearing device 10, and then thread thecartridge cavity closure cap 14 back onto the main body 12. Thecartridge cavity closure cap 14 has a cradle 58 complementary to thespherical shape of the non-outlet end 60 of the fluid cartridge 50 forengaging the non-outlet end 60 of the fluid cartridge 50. The cartridgepiercer 26 is disposed at the opposite end of the cartridge cavity 52from the cartridge insertion aperture 160, and thus as the cartridgecavity closure cap 14 is tightened onto the main body 12, the fluidcartridge 50 is forced toward the outlet end 20 of the drain clearingdevice 10 until the seal 56 is pierced by the cartridge piercer 26,allowing the fluid contained in the fluid cartridge 50 to flow into thevalve mechanism, which is described in greater detail below in respectof FIGS. 3A to 3D. As can be seen, the piercing cannula 62 of thecartridge piercer 26 has a generally frusto-conical shape terminating inan angular plane to define a piercing edge. Without being limited bytheory, it is believed that the generally frusto-conical shape thepiercing cannula 62 facilitates sealing of the cartridge 50 against thepiercing cannula 62. It has been found that a relatively short piercingcannula 62 is desirable, so that it is the last three-quarters of arevolution of the cartridge cavity closure cap 14 which causes the seal56 to be pierced.

Once the quantity of fluid (preferably CO₂) contained in a given fluidcartridge 50 has been exhausted, or the pressure in the fluid cartridge50 has been reduced so that it is insufficient for its purpose (e.g.clearing a drain), the cartridge cavity closure cap 14 can be unscrewedfrom the main body 12, and the fluid cartridge 50 can be removed andreplaced with a new fluid cartridge 50. Thus, a drain clearing devicesuch as the exemplary drain clearing device 10 is reusable. In addition,depending on the particular construction of the fluid cartridges 50, thefluid cartridges 50 may optionally be refilled and resealed for reuse,or may be recycled.

For use in a drain clearing device, different sizes of fluid cartridges50, containing different amounts of fluid, may be advantageous. Threeexemplary sizes of fluid cartridges containing different quantities ofCO₂ gas are illustrated in FIGS. 5A to 5C.

FIG. 5A shows first exemplary fluid cartridge 50A, which would initiallycontain 25 grams of CO₂ at a pressure of approximately 850 pounds persquare inch (approximately 60 bar). The dimensions of the firstexemplary fluid cartridge 50A are as follows:

Dimension Measurement (millimeters) C1 12.0 E1 10.5 F1 3.0 G1 2.4 H112.5 J1 16.5 L1 109.0 R1 (radius) 5.0 W1 25.4

FIG. 5B shows second exemplary fluid cartridge, which would initiallycontain 33 grams of CO₂ at a pressure of approximately 850 pounds persquare inch (approximately 60 bar). The dimensions of the secondexemplary fluid cartridge are as follows:

Dimension Measurement (millimeters) C2 12.0 E2 10.5 F2 3.0 G2 2.4 H212.5 J2 16.5 L2 142.0 R2 (radius) 5.0 W2 25.4

FIG. 5C shows third exemplary fluid cartridge, which would contain 45grams of CO₂ at a pressure of approximately 850 pounds per square inch(approximately 60 bar). The dimensions of the third exemplary fluidcartridge are as follows:

Dimension Measurement (millimeters) C3 12.0 E3 10.5 F3 3.0 G3 2.4 H312.5 J3 16.5 L3 142.0 R3 (radius) 5.0 W3 30.0

Depending on the exemplary fluid cartridge to be used, the dimensions ofthe cartridge cavity 52, cartridge cavity closure cap 14 othercomponents of the drain clearing device 10 would be adapted accordingly.

Referring now to FIGS. 3A to 3D, a valve mechanism forming part of adrain clearing device according to an aspect of the present invention isindicated generally by the reference numeral 80. The valve mechanism 80comprises a housing which, as described above, includes the cartridgereceiving member 22, the fluid chamber member 28, the guide collar 36and the driver receiver member 42, as well as the piercer 26 and thefluid chamber seal 34. The valve mechanism 80 further comprises theplunger biasing member 30, the plunger 32, the plunger actuator 38 andthe driver 40.

A fluid chamber 82 is defined within the housing, and in the illustratedembodiment is defined by the hollow interior volume of the fluid chambermember 28. A fluid chamber inlet 84 into the fluid chamber 82 is definedat the inlet end 28A of the fluid chamber member 28 by a passageway 84in the piercing cannula 62 of the cartridge piercer 26, so that theinterior volume of the fluid chamber 82 is in fluid communication withthe interior of the fluid cartridge 50 when the same is installed. Inthe illustrated embodiment, the cartridge piercer 26 is friction fitinto a receiving collar 86 at the inlet end 22A of the cartridgereceiving member 22, and is supported by the annular edge of the inputend 28A of the fluid chamber member 28. The cartridge seal 24 isfriction fit into the receiving collar 86 on top of the cartridgepiercer 26 to surround the piercing cannula 62. Other suitablearrangements for installing the cartridge piercer 26 and cartridge seal24 may also be used, without departing from the scope of the presentinvention.

An opening 90 at the outlet end 28B of the fluid chamber member 28cooperates with the fluid chamber seal 34 to define a plunger aperture88 in the fluid chamber 82. The plunger 32 is slidably received in theplunger aperture 88 in sealing engagement therewith, as will bedescribed in greater detail below.

The plunger 32 has a closed end 32A and a plunger outlet end 32B. Aplunger fluid passage 92 extends partially along a length of the plunger32 from the plunger outlet end 32B. A peripheral rim 94 surrounds theplunger fluid passage 92 at the plunger outlet end 32B. The plunger hastwo diametrically opposed plunger inlets 96 defined in a longitudinalwall 98 thereof in fluid communication with the plunger fluid passage92. In alternate embodiments, the plunger 32 may have only one plungerinlet, or may have more than two plunger inlets.

As noted above, the plunger 32 is slidably received in the plungeraperture 88. Frictional engagement of an inner annular surface of thefluid chamber seal 34 with the exterior of the longitudinal wall 98 ofthe plunger 32 inhibits the undesired escape of fluid from the fluidchamber 82, so that the plunger 32 is in sealing engagement with theplunger aperture 88. The closed end 32A of the plunger 32 is disposedwithin the interior volume of the fluid chamber 82, and the plunger 32is movable between a fluid retention position (shown in FIG. 3A) inwhich the plunger inlets 96 are isolated from the interior volume of thefluid chamber 82, and a fluid release position (shown in FIG. 3C) inwhich the plunger inlets 96 are in fluid communication with the interiorvolume of the fluid chamber 82. The plunger 32 has an annular stop 100which cooperates with an annular shoulder 102 inside the fluid chambermember 28 and with the fluid chamber seal 34 and the guide collar 36 tolimit the axial range of motion of the plunger 32 and thereby define thefluid retention position and fluid release position. The annular stop100 also serves as an engagement surface for the plunger biasing member30.

As shown in FIG. 3A, the plunger biasing member 30 acts between theplunger 32, specifically the annular stop 100, and the housing, inparticular the annular rim of the cartridge piercer 26, to urge theplunger into the fluid retention position in which the annular stop 100abuts the fluid chamber seal 34. When the plunger 32 is in the fluidretention position, the plunger inlets 96 are outside of the fluidchamber 82 and are therefore isolated therefrom. Conversely, when theplunger 32 is in the fluid release position, as shown in FIG. 3C, theplunger inlets 96 are inside the fluid chamber 82 and therefore are influid communication with the interior volume of the fluid chamber 82.

As noted above, the valve mechanism 80 further includes the plungeractuator 38, which is received within the housing between the plunger 32and the driver 40. More particularly, in the illustrated embodiment theplunger actuator 38 is received in an interior space 102 defined withinthe guide collar 36 and the driver receiver member 42. The plungeractuator 38 has a plunger actuator inlet end 38A and a plunger actuatoroutlet end 38B, and a plunger actuator fluid passage 104 extends throughthe plunger actuator 38 between the plunger actuator inlet end 38A andthe plunger actuator outlet end 38B. The plunger actuator 38 ispositioned with the plunger actuator inlet end 38A facing toward theplunger 32 and the plunger actuator outlet end 38B facing generallytoward the driver 40.

The plunger actuator inlet end 38A is narrower than the plunger actuatoroutlet end 38B, and the plunger actuator inlet end 38A is sized to fitwithin the plunger fluid passage 92. The plunger actuator outlet end hasan annular flange 106, and the outer surface 108 of the plunger actuator38 smoothly tapers from a position axially inward of the annular flange106 to a position axially inward of the plunger actuator outlet end 38B.In the illustrated embodiment, the plunger actuator 38 is not slidinglyreceived within the interior space 102, but has a small amount of playso that it can shift in and out of coaxiality with the other componentsof the valve mechanism 80, as will be described in detail below.

Continuing to refer to FIGS. 3A to 3D, the driver 40 is slidinglyreceived within a central aperture 110 (FIG. 2) in the driver receivermember 42. The driver has a driving end 40A and a driver outlet end 40B,and a driver fluid passage 112 extends through the driver 40 between thedriving end 40A and the driver outlet end 40B.

The driving end 40A of the driver 40 has a driver engagement face 114,and the plunger actuator outlet end 38B has a plunger actuatorengagement face 116. The driver engagement face 114 is shaped to directthe plunger actuator inlet end 38A to engage the peripheral rim 94 atthe plunger outlet end 32B during the first portion of the stroke of thedriver 40 towards the fluid chamber when the valve mechanism is orientedwith the plunger actuator above the driver (as is the case in FIGS. 3Ato 3D). In the illustrated embodiment, the driver engagement face 114and the plunger actuator engagement face 116 are both generally planar,and the driver engagement face 114 is angled away from beingperpendicular to the axis of the driver 40 as defined by its shaft 118(and hence is angled away from perpendicular to the direction of thestroke of the driver 40, as will be described below). As a result of theangling of the driver engagement face 114, when the valve mechanism 80is oriented with the plunger actuator 38 above the driver 40, the axisof the plunger actuator 38 is non-parallel to the shaft 118 of thedriver, and the plunger actuator inlet end 38A is out of alignment withthe plunger fluid passage 92 at the plunger outlet end 32B. Accordingly,as long as the valve mechanism 80 is oriented with the plunger actuator38 above the driver 40, during the first portion of the stroke of thedriver 40 towards the fluid chamber 82, the angle of the driverengagement face 114 will direct the plunger actuator inlet end 38A awayfrom the fluid passage 92 and into engagement with the peripheral rim 94surrounding the plunger fluid passage 92 at the plunger outlet end 32B.

Although in the illustrated embodiment it is the driver engagement face114 that is angled away from being perpendicular to the axis of thedriver 40, in other embodiments the driver engagement face 114 may beperpendicular to the axis of the driver 40 and the plunger actuatorengagement face 116 may be angled away from perpendicular to the axis ofthe plunger actuator 38. Alternatively, both components may be angled,with the driver engagement face 114 angled relative to the axis of thedriver 40 and the plunger actuator engagement face 116 angled relativeto the axis of the plunger actuator 38, to achieve the same effect.

In an alternative embodiment (not shown), the driver engagement face maybe perpendicular to the axis of the driver and the plunger actuatorengagement face may be perpendicular to the axis of the plungeractuator, and either of the driver engagement face or the plungeractuator engagement face may have a projection thereon so that when thevalve mechanism is oriented with the plunger actuator above the driver,the axis of the plunger actuator is non-parallel to the shaft of thedriver, and the plunger actuator inlet end is out of alignment with theplunger fluid passage 92 at the plunger outlet end 32B. Such aprojection could take the form of a ridge or bump on one side of thedriver engagement face or plunger actuator engagement face, or either ofthe driver engagement face or the plunger actuator engagement face maybe a hemispherical surface while the other is a substantially planarsurface perpendicular to the axis of the respective component.

The angling of the driver engagement face 114 away from perpendicular tothe axis of the driver 40 (or angling of the plunger actuator engagementface 114, or both, or other shaping of one or both parts for directingthe plunger actuator inlet end 38A away from the fluid passage 92 andinto engagement with the peripheral rim 94) forms part of a guidemechanism for guiding the plunger actuator 38 into engagement with theplunger 32 to cause the plunger 32 and the plunger actuator 38 to movein unison and move the plunger 32 into the fluid release position duringa first portion of the stroke of the driver 40 towards the fluid chamber84.

The guide mechanism is also operable to guide the plunger actuator inletend 38A to permit the plunger 32 to return to the fluid retentionposition under urging from the plunger biasing member 30 during thesecond portion of the stroke of the driver 40 towards the fluid chamber82 when the valve mechanism 80 is oriented with the plunger actuator 38above the driver 40. To this end, the guide mechanism further comprisesa guide channel 120 defined in the housing.

The guide channel 120 is defined primarily within the guide collar 36,which also includes a plunger bore 122 which slidingly receives theplunger outlet end 32B; a portion of the guide channel 120 is alsodisposed in the driver receiver member 42 immediately adjacent the guidecollar 36. The guide channel 120 has a narrow end adjacent the plungerbore 122 and a wide end within the driver receiver member 42, and theguide channel 120 is coaxial with the plunger bore 122. The guidechannel 120 tapers between the wide end and the narrow end. When thevalve mechanism 80 is oriented with the plunger actuator 38 above thedriver 40, the guide channel 120 will, by way of its position within thehousing and the shape of its surface, guide the plunger actuator inletend 38A into registration with the plunger fluid passage 92 during thesecond portion of the stroke of the driver 40 towards the fluid chamber82. More particularly, as the driver 40 moves into the second portion ofits stroke towards the fluid chamber 82, the smoothly tapered outersurface 108 of the plunger actuator 38 will engage the tapered surfaceof the guide channel 120, centering the plunger actuator 38 within theguide channel 120 so that it is coaxial therewith and hence also coaxialwith the plunger bore 122. Since the plunger actuator inlet end 38A isnarrower than the plunger fluid passage 92, the aforesaid centeringaction brings the plunger actuator inlet end 38A into registration withthe plunger fluid passage 92.

The drain clearing device 10 includes an external actuator. In theillustrated embodiment, the external actuator is the outlet fitting 16,including the end piece 48, which is preferably made from a resilientmaterial to assist in sealing against a drain, such as exemplary drain152. As can be seen in FIGS. 3A to 3D, the end piece 48 has a truncateddome shape, which, because the end piece 48 is resilient, enables theoutlet fitting 16 (including the end piece 48) to sealingly engage adrain, such as the exemplary drain 152.

The outlet fitting 16 has a generally cylindrical outer surface, and hasa plurality of circumferentially spaced, inwardly projecting radial ribs124 which strengthen the outlet fitting 16 and assist in centering itabout the main body 12 when installed. The outlet end 16B of the outletfitting 16 has a cylindrical recess 126 which receives a correspondinglysized outer cylindrical wall 128 on the end piece 48 in a friction fit,so as to secure the end piece 48 to the outlet fitting 16. A pluralityof radially spaced, generally sector-shaped spokes 130 are defined inthe floor of the cylindrical recess 126, and provide additional supportfor the ribs 124.

Concentrically spaced inner and outer cylindrical mounting walls 132,134 on the outlet fitting 16 project toward the inlet end 16A thereof,and define an annular mounting recess 136 therebetween. The annularmounting recess 136 receives the hollow cylindrical mounting end 138 ofthe resilient grommet 44 in a friction fit, thereby movably securing theoutlet fitting 16 to the housing of the drain clearing device 10.

An annular driver engagement shoulder 140 is defined in the innersurface 142 of the inner cylindrical mounting wall 132, which engagesthe driver outlet end 40B of the driver 40. To this end, the driveroutlet end 40B has a slightly smaller diameter than the rest of thedriver shaft 118. This engagement between the driver engagement shoulder140 and the driver outlet end 40B mechanically couples the outletfitting 16 to the driver 40, so that when the outlet fitting 16 movestoward the fluid chamber 82, it will cause axial, sliding movement ofthe driver 40 within the driver receiver member 42. The inner surface142 of the inner cylindrical mounting wall 132 is sloped so that it iswider toward the inlet end 16A of the outlet fitting 16 and narrowertoward the outlet end 16B of the outlet fitting 16, which assists inguiding the driver outlet end 40B of the driver 40 into engagement withthe annular driver engagement shoulder 140 during installation of theoutlet fitting 16.

An outlet fitting fluid passage 144 is defined in the floor of thecylindrical recess 126 and, when the driver outlet end 40B engages theannular driver engagement shoulder 140, the outlet fitting fluid passage144 is in fluid communication with the driver fluid passage 112. Whenthe end piece 48 is installed on the outlet fitting 16, the outletfitting fluid passage 144 opens into a first cylindrical fluid passage146 in the end piece 48, which in turn opens into a second, widercylindrical fluid passage 146 in the end piece 48, which defines anoverall outlet aperture 150 for the drain clearing device 10.

Operation of an exemplary drain clearing device 10 according to anaspect of the present invention will now be described with respect toFIGS. 3A to 3D. Generally speaking, to use the exemplary drain clearingdevice 10, a user would position it so that the outlet end 16A of theoutlet fitting 16 seals the drain to be cleared, and then apply downwardpressure, for example by grasping the main body 12 and pushing ittowards the drain 150, thereby also pushing the main body 12 into theoutlet fitting 16.

In FIG. 3A, the drain clearing device has been placed against anexemplary drain 152, so that the outlet fitting 16, and moreparticularly the resilient end piece 48, is positioned to seal the mouthof the drain 152. No pressure has yet been applied. When clearing adrain with a drain clearing device such as drain clearing device 10, thewater level in the sink whose drain is to be cleared should generally behigh enough to at least cover the end piece 48 (typically about one inchof water). In addition, where the obstructed drain is part of a doublesink, the second drain aperture (i.e. the drain aperture with which thedrain clearing device is not being used) should be temporarilyobstructed to avoid undesirable backflow.

As can be seen, the valve mechanism 80 is oriented with the plungeractuator 38 above the driver 40, and under the influence of gravity, theplunger actuator 38 rests on the driver 40, with the plunger actuatorengagement face 116 in planar engagement with the driver engagement face114. Because the driver engagement face 114 is angled away from beingperpendicular to the axis of the driver 40 as defined by its shaft 118(and hence is angled away from perpendicular to the direction of thestroke of the driver 40, as will be described below), the axis of theplunger actuator 38 is non-parallel to the shaft 118 of the driver, andthe plunger actuator inlet end 38A is out of alignment with the plungerfluid passage 92 at the plunger outlet end 32B.

Reference is now made to FIG. 3B, which shows an initial stage of thefirst portion of the stroke of the driver 40 towards the fluid chamber82. As a user applies downward pressure (indicated by the arrow “D”) tothe main body 12, the main body will move downward relative to theoutlet fitting 16, which is braced against the exemplary drain 152. Thisdownward movement of the main body 12 relative to the outlet fitting 16compresses the resilient grommet 44. Viewed another way, the outletfitting 16 moves upward relative to the main body 12.

Because the annular driver engagement shoulder 140 inside the outletfitting 116 engages the driver outlet end 40B of the driver 40, theoutlet fitting 16 is mechanically coupled thereto, and the relativemovement of the outlet fitting 16 toward the main body 12 (and hencetoward the fluid chamber 82) causes a corresponding sliding movement ofthe driver 40 within the driver receiver member 42, also toward thefluid chamber 82. In turn, because the plunger actuator 38 rests on thedriving end 40A of the driver 40, the movement of the driver 40 towardthe fluid chamber 82 causes the plunger actuator to move toward thetoward the fluid chamber 82, and hence toward the plunger 32. As theplunger actuator 32 moves toward the plunger 32, the angle of the driverengagement face 114 will direct the plunger actuator inlet end 38A awayfrom the plunger fluid passage 92 and into engagement with theperipheral rim 94 surrounding the plunger fluid passage 92 at theplunger outlet end 32B. During this initial stage of the first portionof the stroke of the driver 40 towards the fluid chamber 82, pressurizedfluid in the fluid chamber 82 is trapped therein by cooperation of theannular stop 100 on the plunger 32 and the fluid chamber seal 34.

As the driver 40 continues to move through the first portion of itsstroke and continues to push the plunger actuator 38 towards the plunger32, the plunger actuator inlet end 38A engages the peripheral rim 94 atthe plunger outlet end 32A. The engagement of the plunger actuator inletend 38A with the peripheral rim 94 results in motion of the driver 40,during the remainder of the first portion of its stroke toward the fluidchamber 82, causing the plunger actuator 38 and the plunger 32 and tomove in unison toward the fluid chamber 82. During this subsequent stageof the first portion of the stroke of the driver 40 towards the fluidchamber 82, even though the plunger 32 is moving into the fluid chamber82, the pressurized fluid remains substantially trapped in the fluidchamber 82 by the fluid chamber seal 34.

Turning now to FIG. 3C, which shows the final stage of the first portionof the stroke of the driver 40 toward the fluid chamber 82, the driver40 has driven the plunger actuator 38 to push the plunger 32 into thefluid release position, with the plunger inlets 96 in fluidcommunication with the interior volume of the fluid chamber 82. As canbe seen in FIG. 3C, with the plunger 32 in the fluid release position,the plunger fluid passage 92 is in fluid communication with the plungeractuator fluid passage 104, and the plunger actuator fluid passage 104is in fluid communication with the driver fluid passage 112. As aresult, pressurized fluid in the fluid chamber 82 is able to escapetherefrom by passing through the plunger inlets 96 into the plungerfluid passage 92, from the plunger fluid passage 92 into the plungeractuator fluid passage 104, from the plunger actuator fluid passage 104into the driver fluid passage 112, and then from the driver fluidpassage 112 into the outlet fitting fluid passage 144, and finallythrough the first and second fluid passages 146, 148 in the end piece 46and hence through the outlet aperture 150 and into the drain 152, asindicated by the arrows showing the fluid flow path. Thus, the fluid, solong as it is sufficiently pressurized, will assist in clearing ablockage downstream of the drain. Pressure within the fluid chamber 82is maintained by inflow of pressurized fluid from the fluid cartridge 50by way of the fluid chamber inlet 84.

A valve mechanism 80 according to an aspect of the present inventionprovides for mechanical timing and metering of the amount of fluidreleased, because the plunger 32 is returned from the fluid releaseposition to the fluid retention position as the stroke of the driver 40toward the fluid chamber is completed.

With reference now to FIG. 3D, as the driver 40 continues into thesecond portion of its stroke toward the fluid chamber 82, the plungeractuator 38 also continues to move toward the fluid chamber 82. As theplunger actuator 38 continues to move toward the fluid chamber 82, thesmoothly tapered outer surface 108 of the plunger actuator 38 engagesthe tapered surface of the guide channel 120, centering the plungeractuator 38 within the guide channel 120 and thereby bringing theplunger actuator inlet end 38A into registration with the plunger fluidpassage 92. Because the plunger actuator inlet end 38A is narrower thanthe plunger fluid passage 92, as the driver 40 continues to push theplunger actuator 38 toward the fluid chamber 82, the plunger actuatorinlet end 38A is received within the plunger fluid passage 92. Thispermits sliding movement of the plunger 32 toward the plunger actuator,since such movement is no longer obstructed by engagement of the plungeractuator inlet end 38A with the peripheral rim 94 at the plunger outletend 32B. Thus, as the driver 40 completes the second portion of itsstroke toward the fluid chamber 82, the biasing member 30 urges theplunger 32 away from the fluid chamber 82, with the plunger actuatorinlet end 38A received within the plunger fluid passage 92. The plunger32 is now back into the fluid retention position, with the plungerinlets 96 outside of, and hence isolated from, the fluid chamber 82.Pressurized fluid in the fluid chamber 82 is once again trapped thereinby cooperation of the annular stop 100 on the plunger and the fluidchamber seal 34.

The exemplary valve mechanism 80 described herein provides for a timedand metered fluid release, because a single stroke of the driver 40towards the fluid chamber 82 will release a limited, measured, quantityof fluid, no matter how long the driver 40 is maintained in position atthe completion of its stroke. More particularly, continuing to push thedriver 40 toward the fluid chamber 82 does not release any additionalfluid, because fluid is released only during the first portion of thestroke, and the plunger 32 has returned to the fluid retention positionby the time the stroke is completed. Thus, continuing to push the mainbody 12 toward the outlet fitting 16 will not release more fluid thanthe metered amount.

The amount of fluid released is limited by the size of the plungerinlets 96, and by the parameters of the plunger 32, plunger actuator 38and driver 32, which determines how long the plunger will remain in thefluid release position during a given stroke of the driver 40 toward thefluid chamber 82. Where a valve mechanism according to the presentinvention is to be used in a drain clearing device, as herein shown anddescribed, the cartridge pressure and other parameters should beselected so that the amount of fluid discharged on a singly stroke issufficient to clear at least a typical drain blockage from a typicaldrain, but not so much as to damage the drain. While the speed of thestroke will affect this duration somewhat (i.e. a slower stroke mayrelease slightly more fluid than a longer stroke), as long as sufficientforce is applied to the driver these variations are unlikely to besignificant. For example, where a valve mechanism according to an aspectof the present invention is used in a drain clearing device asillustrated, any variations resulting from differences in thespeed/force with which a user pushes the main body 12 toward the outletfitting 16 while the outlet fitting 16 engages a drain 152 are unlikelyto adversely effect operation of the device. Because the fluid output ismetered, multiple fluid discharges from a single fluid cartridge 50 arepossible.

Following completion of the stroke of the driver 40 towards the fluidchamber 82, as shown in FIG. 3D, upon release of downward pressure onthe main body 12, the resilient grommet 44 will push the outlet fitting16 away from the main body 12 and return the main body 12 and the outletfitting 16 to their original relative positions. This releases theexternal force acting on the driver 40 (by way of the annular driverengagement shoulder 140 in the outlet fitting 16) and driver 40 and theplunger actuator 38 to return to their respective pre-stroke positions(FIG. 3A) under gravity when the valve mechanism 80 is oriented with theplunger actuator 38 above the driver 40. The valve mechanism 80 is nowready for a new stroke of the driver 40 toward the fluid chamber 82.

Reference is now made to FIGS. 4A and 4B. As noted above, in theexemplary embodiment a fluid cartridge 50 is received within a cartridgecavity 52 defined in the main body 12 of the drain clearing device 10.More particularly, the main body 12 defines a cartridge insertionaperture 160 at one end of the main body 12, namely the reservoir end 18of the drain clearing device 10. As was explained above, the cartridgepiercer 26 (not shown in FIGS. 4A and 4B) is located at the opposite endof the cartridge cavity 52 from the cartridge insertion aperture 160, sothat as the cartridge cavity closure cap 14 is secured to the main body12, it will obstruct the cartridge insertion aperture 16 and push thethin metal seal 56 at the outlet end of the fluid cartridge 50 intoengagement with the cartridge piercer 26. At the same time, securing thecartridge cavity closure cap 14 to the main body 12 will close thecartridge cavity 52. In this context, the term “close” denotes a sealwhich, while not necessarily a perfect hermetic seal, generallymaintains the pressure in the cartridge cavity 52 and permits only verysmall amounts of fluid to escape over a prolonged period. FIG. 4A showsthe cartridge cavity closure cap fully secured to the main body 12.

An inspection aperture 162 is defined through the cradle 58 of thecartridge cavity closure cap 14, to assist a user in determiningvisually whether or not a fluid cartridge is contained within thecartridge cavity 52. Where no cartridge is contained in the cartridgecavity 52, the inspection aperture 162 will be dark, and where a fluidcartridge 50 is contained within the cartridge cavity 52, the bottom ornon-outlet end 60 of the fluid cartridge 50 will be visible through theinspection aperture 162. To enhance visibility, the non-outlet end 60 ofthe fluid cartridge 50 can be painted with a color that contrasts withthe color of the outside of the cradle 58 of the cartridge cavityclosure cap 14. Because drain blockages are infrequent, the inspectionaperture is advantageous, since it allows a user to check whether acartridge is already loaded in the cartridge cavity 52 before removingthe cartridge cavity closure cap 14, since removing the cap would allowa still-charged cartridge to vent to the atmosphere, wasting theremaining fluid therein. When the cartridge cavity closure cap 14 isfully secured to the main body 12, the non-outlet end 60 of the fluidcartridge 50 seats against the correspondingly shaped cradle 50 on thecartridge cavity closure cap 14, effectively sealing the inspectionaperture 162.

The cartridge cavity closure cap 14 is constrained, during removalthereof from the main body 12, to move through an intermediate position,as shown in FIG. 4B. In the intermediate position, the fluid cartridge50 is released from engagement with the cartridge piercer 26 while thecartridge cavity closure cap 14 remains secured to the main body 12, andthe cartridge cavity 52 is vented to the ambient atmosphere. As can beseen in FIG. 4B, the cartridge cavity closure cap 14 has been partiallyunscrewed from the main body 12, and the fluid cartridge 50 has, as aresult of expulsion of some of the pressurized fluid contained therein,pushed upward away from the cartridge piercer 26, so that the non-outletend 60 of the fluid cartridge 50 continues to seat against thecorrespondingly shaped cradle 50 on the cartridge cavity closure cap 14and effectively seal the inspection aperture 162.

In the illustrated embodiment, the cartridge insertion aperture 160 isdefined by a hollow threaded shaft portion 164, which has a threadedouter surface 166, and the cartridge cavity closure cap has acorrespondingly threaded inner surface 168 (best seen in FIG. 4B) forthreaded engagement with the threaded shaft portion 164. A vent 170 isdefined in the threaded shaft portion 164 in fluid communication withthe cartridge cavity 52.

Removal of the cartridge cavity closure cap 14 consists of unscrewingthe cartridge cavity closure cap 14 from the threaded shaft portion 164of the main body 12. As a user unscrews the cartridge cavity closure cap14, it will reach a partially unscrewed position (i.e. between beingfully tightened (FIG. 4A) and being fully unscrewed and removed from thethreaded shaft portion 164 (not shown)). In the partially unscrewedposition, the cartridge cavity closure cap 14 has been unscrewed pastthe vent 170 while remaining threadedly secured to the threaded shaftportion 164 of the main body 12. Because the vent 170 has been exposedto the ambient atmosphere, pressurized fluid can escape from the fluidcartridge 50 into the cartridge cavity 52 and then into the atmospherevia the vent 170, while the fluid cartridge 50 remains safely trapped inthe cartridge cavity 52 by the cartridge cavity end cap 14. In theabsence of the vent 170, if a user were to unscrew the cartridge cavityend cap 14 while the cartridge cavity 52 still contained a fluidcartridge 50 with a significant volume of pressurized fluid, the fluidcartridge 50 could be violently propelled out of the cartridge cavity 52at the moment the cartridge cavity end cap 14 was completely unscrewed,posing a serious risk to life and safety. In the process, the fluidcartridge 50 might also impart a substantial velocity to the cartridgecavity end cap 14, creating further danger. Inclusion of the vent 170substantially obviates this risk.

The above described system for venting a cartridge cavity prior tocomplete removal of the cartridge cavity closure cap is not limited todrain clearing devices, but may be incorporated into any cartridge-baseddevice for controlled release of pressurized fluid having a similarconstruction. Generally speaking, devices where the above-describedventing system is useful will include a main body defining a cartridgecavity and a cartridge insertion aperture at one end thereof, acartridge piercer disposed at an opposite end of the cartridge cavityfrom the cartridge insertion aperture, an outlet, a valve mechanismincluding an inlet connectable in fluid communication with a cartridgereceived in the cartridge cavity and connected in fluid communicationwith the outlet for selectively permitting gas from the cartridge to beexpelled from the outlet, and a cartridge cavity closure cap removablysecurable to the main body to obstruct the cartridge insertion apertureand push an outlet end of the fluid cartridge into engagement with thecartridge piercer and close the cartridge cavity. When theaforementioned venting system is incorporated into such a device, thecartridge cavity closure cap of the device will be constrained, duringremoval thereof from the main body, to move through an intermediateposition in which the fluid cartridge is released from engagement withthe cartridge piercer while the cartridge cavity closure cap remainssecured to the main body and the cartridge cavity is vented to theambient environment.

Components of a drain clearing device according to aspects of thepresent invention may be made from suitable types of metal or plastic.Fluid cartridges 50 are preferably made from metal. Components such asthe cartridge receiving member 22, fluid chamber member 28, guide collar36 and driver receiver member 42 may be made from plastic and designedto snap-fit together, or may be maintained in their respective positionswithin the main body 12 by shoulders within the main body 12 and on theoutlet end cap 46 corresponding to respective shoulders on the cartridgereceiving member 22 and the driver receiver member 42. For example, withreference to FIG. 3, in the illustrated embodiment the cartridgereceiving member 22 has inner and outer annular shoulders 180, 182,respectively, which engage corresponding inner and outer annularshoulders 186, 184 on the main body 12, and the outlet end cap 46similarly has an annular shoulder 188 which mates with an annularshoulder 190 on the driver receiver member 42. The main body 12 may beformed from two plastic halves, which may be ultrasonically weldedtogether. The plunger actuator 38 is preferably made from a materialhaving sufficient mass, given its size, so that when the valve mechanism80 is oriented with the plunger actuator 38 above the driver 40, theplunger actuator 38 will consistently fall into engagement with thedriving end 40A of the driver 40 as described above. As such, suitablemetals are preferred as the material for the plunger actuator 38.Suitably durable metal is also preferred as the material for thecartridge piercer 26.

It will be appreciated that valve mechanisms according to aspects of thepresent invention, such as exemplary valve mechanism 80, are not limitedto use in drain clearing devices, and may be used in other devices wheresuch mechanical fluid metering would be advantageous.

Moreover, while embodiments of a drain clearing device according to anaspect of the present invention have been described as receivingremovable and replaceable fluid cartridges, it is within thecontemplation of the inventor that alternate embodiments may comprise adisposable unit with an integral, pre-filled fluid reservoir.

Furthermore, while the exemplary plunger 32 and driver 40 have beenshown as having generally cylindrical features, the exemplary plunger32, plunger actuator 38 and driver 40 have been shown as being generallysymmetrical (other than the driving end 40A of the driver 40), othersuitable shapes, both symmetrical and asymmetrical, may also be used solong as they do not inhibit the function of the mechanism. For example,and without limitation, the shaft of the driver may have a triangular,rectangular or hexagonal perimeter, and parts of the plunger may besimilarly configured. In respect of the plunger, sharp corners should beavoided on portions of the exterior surface that will engage the fluidchamber seal, as such corners typically adversely affect sealing.

In addition, while the plunger 32, plunger actuator 38 and driver 40have been shown with individual respective fluid passages 92, 104 and112, one or more of these components may, with suitable modifications,be provided with more than one fluid passage.

One or more currently preferred embodiments have been described by wayof example. It will be apparent to persons skilled in the art that anumber of variations and modifications can be made without departingfrom the scope of the invention as defined in the claims.

The table below sets out a listing of the reference numerals usedherein, as well as the part or feature identified by that referencenumeral, for ease of reference. No limitation is implied by this table.

Reference Part/Feature Description  10 Drain clearing device (overall) 12 Main body of drain clearing device  14 Cartridge cavity closure cap 16 Outlet fitting  16A Inlet end of outlet fitting  16B Outlet end ofoutlet fitting  18 Reservoir end of drain clearing device  20 Outlet endof drain clearing device  22 Cartridge receiving member  22A Inlet endof cartridge receiving member  24 Cartridge seal  26 Cartridge piercer 28 Fluid chamber member 28  28A Inlet end of fluid chamber member  28BOutlet end of fluid chamber member  30 Plunger biasing member  32Plunger  32A Closed end of plunger  32B Plunger outlet end  34 Fluidchamber seal 34  36 Guide collar  38 Plunger actuator  38A Plungeractuator inlet end  38B Plunger actuator outlet end  40 Driver  40ADriving end of driver  40B Driver outlet end  42 Driver receiver member 44 Grommet  46 Outlet end cap  48 End piece for outlet fitting  50Fluid cartridge  50A First exemplary fluid cartridge  50B Secondexemplary fluid cartridge  50C Third exemplary fluid cartridge  52Cavity in main body  54 Generally cylindrical metal canister  56 Thinmetal seal on generally cylindrical metal canister  58 Cradle incartridge cavity closure cap  60 Non-outlet end of fluid cartridge  62Piercer cannula  80 Valve mechanism generally  82 Fluid chamber  84Fluid chamber inlet/passageway in cartridge piercer  86 Receiving collarat inlet end of cartridge receiving member  88 Plunger aperture in fluidchamber  90 Opening at outlet end of fluid chamber member  92 Plungerfluid passage  94 Peripheral rim surrounding plunger fluid passage  96Plunger inlets  98 Longitudinal wall of plunger 100 Annular stop onplunger 102 Interior space defined within guide collar and driverreceiver member 104 Plunger actuator fluid passage 106 Annular flange atplunger actuator outlet end 108 Outer surface of plunger actuator 110Central aperture in driver receiver member 112 Driver fluid passage 114Driver engagement face 116 Plunger actuator engagement face 118 Shaft ofdriver 120 Guide channel 122 Plunger bore in guide collar 124 Inwardlyprojecting ribs on outlet fitting 126 Cylindrical recess in outlet endof outlet fitting 128 Outer cylindrical wall on end piece 130Sector-shaped spokes defined in floor of cylindrical recess in outletfitting 132 Inner cylindrical mounting wall on outlet fitting 134 Outercylindrical mounting wall on outlet fitting 136 Annular mounting recessbetween inner and outer cylindrical mounting walls 138 Cylindricalmounting end of grommet 140 Annular driver engagement shoulder definedin inner surface of inner cylindrical mounting wall on outlet fitting142 inner surface of inner cylindrical mounting wall on outlet fitting144 Outlet fitting fluid passage 146 First cylindrical fluid passage inend piece 148 Second cylindrical fluid passage in end piece 150 Overalloutlet aperture 152 Exemplary drain 160 Cartridge insertion aperture inmain body 162 Inspection aperture 164 Hollow threaded shaft portiondefining cartridge insertion aperture 166 Threaded outer surface ofthreaded shaft portion 168 Threaded inner surface of cartridge cavityclosure cap 170 Vent defined in threaded shaft portion 180 Inner annularshoulder on cartridge receiving member 182 Outer annular shoulder oncartridge receiving member 184 Outer annular shoulder on main body 186Inner annular shoulder on main body 188 Annular shoulder on outlet endcap 190 Annular shoulder on driver receiver member

1. A valve mechanism for controlling release of pressurized fluid,comprising: a housing; a fluid chamber defined within the housing, thefluid chamber having a fluid chamber inlet and having a plunger apertureand defining an interior volume; a plunger having a closed end and aplunger outlet end, the plunger having at least one plunger fluidpassage extending partially along a length of the plunger from theplunger outlet end, the plunger having at least one plunger inletdefined in a longitudinal wall thereof in fluid communication with theat least one plunger fluid passage; the plunger being slidably receivedin the plunger aperture in sealing engagement therewith the closed endwithin the interior volume of the fluid chamber so as to be movablebetween a fluid retention position in which the at least one plungerinlet is isolated from the interior volume of the fluid chamber and afluid release position in which the at least one plunger inlet is influid communication with the interior volume of the fluid chamber; aplunger biasing member acting between the plunger and the housing tobias the plunger into the fluid retention position; a driver having adriving end and a driver outlet end and having at least one driver fluidpassage extending therethrough between the driving end and the driveroutlet end, the driver being slidably received within the housing; aplunger actuator having a plunger actuator inlet end and a plungeractuator outlet end, the plunger actuator having at least one plungeractuator fluid passage extending therethrough between the plungeractuator inlet end and the plunger actuator outlet end, the plungeractuator received within the housing between the plunger and the driver;and a guide mechanism for: guiding the plunger actuator into engagementwith the plunger to cause the plunger and the plunger actuator to movein unison and move the plunger into the fluid release position during afirst portion of a stroke of the driver towards the fluid chamber whenthe valve mechanism is oriented with the plunger actuator above thedriver; and further guiding the plunger actuator to permit the plungerto return to the fluid retention position under urging from the plungerbiasing member during a second portion of the stroke of the drivertowards the fluid chamber when the valve mechanism is oriented with theplunger actuator above the driver; wherein at least when the plunger isin the fluid release position, the at least one plunger fluid passage isin fluid communication with the at least one plunger actuator fluidpassage and the at least one plunger actuator fluid passage is in fluidcommunication with the at least one driver fluid passage.
 2. A drainclearing device, comprising: a valve mechanism according to claim 1; anda fluid reservoir having a sufficient quantity of sufficientlypressurized gas disposed therein, the fluid reservoir being in fluidcommunication with the fluid chamber inlet.
 3. A drain clearing deviceaccording to claim 2, wherein the fluid reservoir consists of a separatecartridge secured within a cartridge cavity in a main body of the drainclearing device.
 4. A drain clearing device according to claim 2,further comprising: an external actuator movably secured to the housingand mechanically coupled to the driver to cause sliding movement of thedriver toward the fluid chamber when the external actuator moves towardsthe fluid chamber.
 5. A drain clearing device according to claim 4,wherein the external actuator is an outlet fitting for sealinglyengaging a drain, the outlet fitting being secured to an outlet end ofthe drain clearing device and having an outlet aperture in fluidcommunication with the driver fluid passage.
 6. A drain clearing deviceaccording to claim 3, further comprising: a cartridge insertion apertureat one end of the main body; a cartridge piercer disposed at an oppositeend of the cartridge cavity from the cartridge insertion aperture; and acartridge cavity closure cap removably securable to the main body toobstruct the cartridge insertion aperture and push an outlet end of thefluid cartridge into engagement with the cartridge piercer and close thecartridge cavity; wherein the cartridge cavity closure cap isconstrained, during removal thereof from the main body, to move throughan intermediate position in which the fluid cartridge is released fromengagement with the cartridge piercer while the cartridge cavity closurecap remains secured to the main body and the cartridge cavity is ventedto ambient.
 7. The drain clearing device of claim 6, wherein: thecartridge insertion aperture is defined by a hollow threaded shaftportion having at least one vent defined therein in fluid communicationwith the cartridge cavity; the cartridge cavity closure cap iscorrespondingly threaded for threaded engagement with the threaded shaftportion; and removal of the cartridge cavity closure cap consists ofunscrewing the cartridge cavity closure cap from the threaded shaftportion of the main body, and wherein in the intermediate position thecartridge cavity closure cap has been unscrewed past the at least onevent to expose the at least one vent while the cartridge cavity closurecap remains threadedly secured to the main body.
 8. A device forcontrolled release of pressurized fluid, comprising: a main body, themain body defining a cartridge cavity and a cartridge insertion apertureat one end of the main body; a cartridge piercer disposed at an oppositeend of the cartridge cavity from the cartridge insertion aperture; anoutlet; a valve mechanism in fluid communication with the outlet forselectively permitting gas from the cartridge to be expelled from theoutlet, the valve mechanism including an inlet connectable in fluidcommunication with a cartridge received in the cartridge cavity; and acartridge cavity closure cap removably securable to the main body toobstruct the cartridge insertion aperture and push an outlet end of thefluid cartridge into engagement with the cartridge piercer and close thecartridge cavity; wherein the cartridge cavity closure cap isconstrained, during removal thereof from the main body, to move throughan intermediate position in which the fluid cartridge is released fromengagement with the cartridge piercer while the cartridge cavity closurecap remains secured to the main body and the cartridge cavity is ventedto ambient.
 9. The device for controlled release of pressurized fluid ofclaim 8, wherein: the cartridge insertion aperture is defined by ahollow threaded shaft portion having at least one vent defined thereinin fluid communication with the cartridge cavity; the cartridge cavityclosure cap is correspondingly threaded for threaded engagement with thethreaded shaft portion; and removal of the cartridge cavity closure capconsists of unscrewing the cartridge cavity closure cap from thethreaded shaft portion of the main body, and wherein in the intermediateposition the cartridge cavity closure cap has been unscrewed past the atleast one vent to expose the at least one vent while the cartridgecavity closure cap remains threadedly secured to the main body.
 10. Thedevice for controlled release of pressurized fluid of claim 8, whereinthe device is a drain clearing device.